The anti-anesthetic action of idazoxan

A possible anti-anesthetic effect of idazoxan using the depth versus latency of cortical cellular response and somatosensory evoked potentials as indices of anesthesia was studied. With the administration of 10 mg/kg (i.p.) idazoxan, a potent and selective alpha 2-adrenoceptor antagonist, to an anesthetized rat with 1.25-1.5 g/kg (i.p.) urethane, the modal latency of somatosensory cortical responses to electrical stimulation of the forepaw (0-90 V, 1 Hz) was shortened to 87 +/- 3.6% (mean +/- S.D.; n = 3) of the baseline value. The number of units firing increased by 259 +/- 98.5% (n = 3). The combined parameter (1/L x Pi; L, latency; Pi, initial positive wave) of the somatosensory evoked potentials was enhanced to 125.0 +/- 16.2% (n = 19) versus saline (98.9 +/- 25.6%; n = 18) during the desynchronized electroencephalogram (EEG). The initial negative component (Ni) of the somatosensory cortical response was increased to 192.0 +/- 83.1% (n = 19) and 134.8 +/- 36.9% (n = 19) during the synchronized and desynchronized EEG, respectively. Thus idazoxan appears to produce effects resembling a "lightening of anesthesia." This may provide the impetus for further studies on the possibility of using alpha 2-adrenoceptor antagonists in the recovery from certain types of anesthetic agents.